21381

Appears in sequences

• Integers k such that k*28*c + 1 is prime for c = 1, 2, 4, 7 and 14.at n=11A067199
• a(n) = p^2 - sum of digits of p^p, where p = prime(n).at n=35A140499
• Expansion of 1/(1-x-x^2-x^3-x^4+x^5+x^6+x^7).at n=17A257934
• Total number of parts coprime to n in the partitions of n into 7 parts.at n=45A363325
• The number of lattice points in the 2D plane contained between the curve y=x^2/4 and the line y=n^2, inclusive, where n is a positive integer.at n=20A385730
• Euler transform of A016116 = 2^floor(n/2).at n=19A392561